172
FXUS65 KBYZ 061838
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
1238 PM MDT SAT JUN 6 2026
KEY MESSAGES
- LATE DAY ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS. A FEW
THUNDERSTORMS MAY BECOME STRONG TO SEVERE OVER EAST CENTRAL
MONTANA (THINK MUSSELSHELL TO NORTHERN CUSTER COUNTY).
- SCATTERED SHOWERS AND THUNDERSTORMS SUNDAY. SEVERE THUNDERSTORMS
ARE POSSIBLE OVER SOUTHEASTERN MONTANA AND NORTH CENTRAL WYOMING.
- MAINLY DRY MONDAY; THEN A DAILY CHANCE OF SHOWERS AND
THUNDERSTORMS REST OF WORK WEEK.
DISCUSSION
NEXT 7 DAYS (THROUGH FRIDAY)...
SATELLITE IMAGERY SHOWED AN UPPER LOW OVER THE PACIFIC NW WITH
SOUTHWEST FLOW OVER OUR REGION. THERE WERE INDICATIONS OF ENERGY
EJECTING FROM THE BOTTOM OF THE PARENT LOW AND TRACKING INTO
WESTERN MONTANA AND NORTHWEST WYOMING. THESE PERTURBATIONS ARE
EXPECTED TO TRIGGER CONVECTION THROUGH THE AFTERNOON OVER SOUTH
CENTRAL MONTANA WHICH WILL MOVE NORTHEAST INTO A MOISTURE RICH
ENVIRONMENT LATE TODAY. MUCAPE VALUES FROM 500-1250 J/KG ARE
PROGGED BY MID AFTERNOON OVER MUCH OF OUR CWA, HIGHEST TOWARD
ROSEBUD/CUSTER COUNTIES. MEAN EFFECTIVE SHEAR WILL RANGE FROM 25
TO 45 KTS WHILE MODEST UPDRAFT HELICITY IS PROGGED FROM WHEATLAND
TO MUSSELSHELL, WITH HIGHER VALUES RAMPING UP THIS EVENING FROM
NORTHERN CUSTER INTO NORTHEAST MONTANA. SOUNDINGS LEAN HEAVILY
TOWARD INVERTED V'S. THIS SUGGEST AN ISOLATED WIND THREAT (60+
MPH) AND A LESSER THREAT OF ANY HAIL FOR OUR CWA. LARGE HAIL
LOOKS MUCH BETTER WITH SIGNIFICANT HELICITY INTO NE MT THIS
EVENING PUSHING INTO NORTH DAKOTA TOWARD WILLISTON. SPC CURRENTLY
HAS MARGINAL SEVERE AREA OVER PORTIONS OF OUR CENTRAL AND EASTERN
CWA FOR LATE TODAY WHICH LOOKS REASONABLE.
A COOLER AIR MASS WITH NORTHERLY WINDS WILL DROP INTO OUR CWA THIS
EVENING, THEN PUSH ALL THE WAY THROUGH TO OUR SOUTHEAST SECTIONS
BY SUNDAY MORNING AS THE PARENT UPPER LOW OVER THE PAC NW LIFTS
THROUGH WESTERN MT INTO SOUTHERN SASKATCHEWAN SUNDAY. AN AXIS OF
INSTABILITY FROM THE WESTERN DAKOTAS INTO SOUTHEAST MT IS EXPECTED
WITH DECENT FORCING FROM THE COLD FRONT AND ASSOCIATED JET
ENERGY ALOFT. STRONG DEEP LAYER SHEAR SHOULD LEAD TO A LARGE
HAIL/DAMAGING WIND THREAT OVER EASTERN PORTIONS OF OUR CWA AND
POSSIBLY INTO SHERIDAN COUNTY, WY. LATEST HELICITY PROGGS ARE
PEGGING POWDER RIVER AND CARTER COUNTIES. HOW FAR WEST THIS THREAT
IS DEPENDS ON HOW MUCH THE COOLER AIR MASS GETS INTO OUR AREA
LIMITING INSTABILITY. AT ANY RATE, OUR SE MT SECTION IS UNDER SPC
SLIGHT RISK TO ENHANCED FOR SEVERE WEATHER SUNDAY AFTERNOON AND
EARLY EVENING. THIS MAY BE SITUATION WHICH IS IN HIGH FLUX AS MANY
VARIABLES WILL BE IN PLAY. SOMETHING TO CLOSELY MONITOR FOR THOSE
WITH PLANS SUNDAY.
MUCH DRIER AIR MOVES IN BEHIND THE WEEKEND SYSTEM FOR MONDAY AS
A WEAK RIDGE DEVELOPS. FOR MID WEEK WE COME UNDER THE INFLUENCE
OF ANOTHER UPPER LEVEL TROUGH DEVELOPING OVER THE ROCKIES. THIS
WILL BRING A DAILY CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH
THE REST OF THE WORK WEEK...MOSTLY GARDEN VARIETY WITH LITTLE
CHANCE OF SEVERE STORMS.
AFTER HIGHS IN THE 80S AND 90S TODAY, LOOK FOR COOLING TO 60S
OVER THE WEST TO LOW 80S OVER THE EAST TOMORROW. TEMPERATURES
WILL THEN INCREASE TO 70S AND 80S MONDAY AND TUESDAY BEFORE
COOLING INTO THE UPPER 60S TO MID 70S FOR REST OF WEEK. BT
AVIATION
18Z DISCUSSION...
VFR CONDITIONS WILL PREVAIL FOR MOST OF THE PERIOD. WINDS OUT OF
THE ESE WILL FLIP TO N BEHIND A FROPA WHICH SHOULD MOVE THROUGH
KBIL AROUND 00Z AND KSHR AROUND 01Z. GUSTS MAY REACH UP TO 20 KTS
WITH THE FROPA.
THE MAIN CONCERN FOR THE PERIOD IS FOR STRONG TO SEVERE STORMS
BETWEEN 22Z AND 04Z. CIGS AND VIS IN AND NEAR THE STORMS WILL
REMAIN VFR BUT THE MAIN CONCERN IS WINDS. CONDITIONS ARE FAVORABLE
FOR THE DEVELOPMENT OF DRY MICROBURSTS UNDER AND NEAR CONVECTION
AS WELL AS OUTFLOW BOUNDARIES EXTENDING WELL OUT AWAY FROM ANY
STORM. STRONG ERRATIC WINDS MAY LOCALLY GUST UP TO 60 KTS NEAR
KMLS AND 50 KTS NEAR KBIL AND KSHR. WINDS IN THE TAFS WE KEPT
SLIGHTLY LOWER DUE TO THE HIGHER CONFIDENCE IN THOSE SPEEDS. ALL
CONVECTION SHOULD BE OUT OF THE FORECAST AREA BY 05Z. WMR
PRELIMINARY POINT TEMP/POPS
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 057/075 044/080 055/079 050/068 047/070 048/070 048/072
24/T 20/B 03/T 75/T 34/T 22/T 22/T
LVM 048/068 035/075 047/070 039/059 036/063 039/066 039/066
34/T 10/B 08/T 97/T 43/T 23/T 33/T
HDN 054/077 041/081 053/082 048/068 045/069 046/070 046/071
24/T 20/B 02/T 76/T 43/T 22/T 22/T
MLS 057/079 045/078 057/084 053/068 049/067 049/069 048/070
35/T 40/U 22/T 55/T 33/T 22/T 12/W
4BQ 059/082 046/081 059/087 051/066 047/065 048/068 048/069
25/T 50/U 20/B 77/T 33/T 22/T 22/T
BHK 059/083 044/077 054/087 051/066 046/065 046/067 045/067
34/T 50/U 21/B 46/T 34/T 22/T 22/W
SHR 053/080 039/083 050/082 045/065 040/066 041/067 042/069
25/T 40/U 12/T 78/T 43/T 23/T 33/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
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